*4.1.2 Thermal desorption by vacuum*

Removal of TCA and other compounds by thermal desorption involves increased temperature to enhance the volatilization of contaminants from the cork material, which is facilitated by vacuum [89]. The desorption process requires temperatures above the boiling points of the haloanisoles to convert the contaminants to a gaseous state. This temperature for TCA at atmospheric pressure (1 bar) is about 240°C, which can compromise the composition of cork material. At the same time, boiling points can be substantially decreased by applying a vacuum: for example, 0.1 mbar pressure lowers the boiling point of TCA to 19.5°C. The desorption process can be carried out at a deeper vacuum of 0.01 mbar or lower, which further facilitates the volatilization of TCA. As a result, desorption of TCA and other contaminants can be performed at moderate temperatures if the proper vacuum level is applied [90]. In addition, the preliminary "recrystallization" of TCA (boiling corks in water and subsequent drying) before the thermal desorption process allegedly enhances the removal of pollutant [91]. A recent example of industrial application of thermal desorption processes is Naturity® technology (Amorim Cork), which allows the extraction of TCA and similar compounds from natural cork stoppers with high efficiency.
